Check valve

ABSTRACT

Disclosed is a new and improved check valve for use in applications such as spray drying, for example. The check valve assembly includes a valve member or piston mounted for movement within an axial bore defined within the valve body. The piston controls the flow of fluid through the valve body and opens by moving in an upstream direction opposite the direction of fluid flow so as to minimize the pressure drop across the valve assembly.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The subject invention relates to fluid control devices, and moreparticularly to, a check valve assembly with a valve member mounted toopen by moving in an upstream direction opposite the direction of fluidflow so as to minimize the pressure drop across the valve assembly.

2. Background of the Related Art

A liquid spray system generally includes a pump, a pressure regulator orflow regulator, a check valve, and a spray nozzle or metering orifice. Aprior art liquid spray system that includes a check valve and a spraynozzle is disclosed in commonly owned U.S. Pat. No. 5,323,807 to Gauldet al., the disclosure of which is herein incorporated by reference.

In a typical liquid spray system, the pump generally supplies liquid atan initial pressure to a flow regulator. The flow regulator then metersor controls the flow rate and/or adjusts the fluid pressure to a desiredsupply pressure for the spray system: The spray nozzle typicallyconverts the metered fluid into a fine mist or other distribution ofsmall droplets having a desired droplet size, volume distribution, andflow rate. For certain applications, the spray system also includes acheck valve or shut-off valve which provides precision in the startingand stopping of the fluid flow, and minimizes dripping that can occurwhen the flow is suspended and/or initiated. The check/shut-off valvetypically functions to suspend fluid flow at a predetermined pressure toprevent undesired spray quality and/or the dripping of excess sprayafter the liquid flow is suspended. The check/shut-off valve is alsogenerally configured to open and start the spray only when apredetermined pressure is reached so as to achieve a consistent sprayquality.

The operating or opening pressure of a typical check valve assembly isusually significantly lower than the nozzle operating pressure in orderto minimize pump capacity or pressure requirements. For example, it maybe necessary to supply 135 psi of pump pressure to hold a check valveopen and to maintain 100 psi in the spray nozzle of a domestic oilburner. Thus, the pressure drop or operating pressure of such a checkvalve is 35 psi.

Pressure loss through or across a check valve is an important factor invalve design and use. Pressure loss is typically dependent upon thedesign of the valve and the nozzle or orifice opening, and results in aflow rate loss at the nozzle. The pressure loss can be due to frictionbetween moving components of the valve assembly, contraction orexpansion, and eddies formed as liquid flows through the valve assembly.The pressure loss associated with the valve generally increases with adecrease in the amount the valve opens and vise versa.

U.S. Pat. No. 4,172,465 to Dashner discloses a conventional check valvethat has a semi-spherical valve member which is movable in an axialdirection between a closed position in engagement with a conical valveseat and an open position spaced axially from the valve seat. Opening ofthe valve is dependent on the differential pressure across the valveseat. That is, the valve opens when the pressure applied to thesemi-spherical valve member is sufficient to overcome the resistance ofthe biasing spring. As is commonplace among prior art check valves, thevalve member moves in the downstream direction (i.e., in the directionof the fluid flow) away from the valve seat, thereby allowing fluid topass between the periphery of the valve member and the valve body.

A disadvantage associated with the check valve disclosed in the Dashnerpatent, as well as other prior art check valves, is that because thevalve opens towards the outlet, the valve spring pressure works againstthe inlet fluid pressure. As a result, at low operating pressures, thevalve member has a tendency to oscillate and disrupt the ability toachieve the constant flow requirements of the spray system, and maycause damage to the valve sealing faces, thereby degrading the valve.Additionally, since the valve member remains at least partially withinthe fluid flow path, the available annular flow area is reduced,resulting in an increase in the flow velocity and pressure loss acrossthe valve.

There is a need therefore, to provide a check valve assembly for use ina variety of applications that includes a valve member which opens bymoving in an upstream direction, rather than a downstream direction, soas to minimize the pressure drop across the valve assembly, and toprevent valve oscillation at low operating pressures.

SUMMARY OF THE INVENTION

The subject application is directed to a new and improved check valvefor use in applications such as spray drying, for example. The checkvalve disclosed herein includes a valve body which defines an axial boreand has opposed upstream and downstream ends, and a piston membermounted for movement within the axial bore for controlling the flow offluid through the body.

The upstream end of the valve body includes a fluid inlet and thedownstream end includes a fluid outlet and defines an sealing facepositioned adjacent to the axial bore. The valve body further includesat least one flow passage for facilitating fluid communication betweenthe fluid inlet and the fluid outlet.

The piston member has opposed upstream and downstream ends and ismounted for movement between an open position and a closed position. Thedownstream end of the piston member is spaced from the interior sealingface of the valve body in the open position to permit fluid flow throughthe valve body. In the closed position, the downstream end of the pistonmember engages the interior sealing face of valve body to suspend theflow of fluid through the valve body. In a representative embodiment,the downstream end of the piston member includes a sealing ring forengagement with the interior sealing surface of the valve body.

The valve assembly further includes a biasing mechanism operativelyassociated with the piston member for urging the piston member to theclosed position. In a representative embodiment, the biasing mechanismis disposed within the axial bore of the valve body adjacent to theupstream end of the piston member. Preferably, the biasing mechanismincludes a spring element. It is presently envisioned that the springelement is a metal helical spring. Alternatively, the biasing mechanismcan include a gas contained within the axial bore and compressed whenthe piston member is in the open position.

Preferably, a port is formed in the valve body, and the port extendsradially from an exterior of the valve body to the axial bore. The portallows gas to be exhausted from the axial bore when the piston moves tothe open position.

The subject disclosure is also directed to a valve assembly whichincludes a valve body that defines an axial bore and has opposedupstream and downstream ends. The upstream end of the valve bodyincludes a fluid inlet and the downstream end includes a fluid outlet.The valve body also defines a series of flow passages which arepositioned radially outward of the axial bore and extend axially betweenthe fluid inlet and the fluid outlet;

The valve assembly further includes an elongated piston member and abiasing mechanism, each being disposed at least partially within theaxial bore of the valve body. The piston member has opposed upstream anddownstream ends and is mounted for movement between an open position anda closed position. The biasing mechanism is operatively associated withthe piston member and for urges the piston member to the closedposition.

The valve assembly further includes retainer element that is engagedwith the downstream end of the valve body and defines an interiorsealing face adjacent to the axial bore. The downstream end of thepiston member is spaced from the interior sealing face of the retainermember in the open position to permit fluid flow through the valve body.However, in the closed position, the downstream end of the piston memberengages with the interior sealing face of retainer member to suspend theflow of fluid through the valve body.

Those skilled in the art will readily appreciate that the subject checkvalve is adapted and configured to open in the upstream direction,opposite that of the product flow, to minimize the pressure drop acrossthe valve assembly, and to prevent valve oscillation at low operatingpressures. These and other unique features of the check valve disclosedherein will become more readily apparent from the following description,the accompanying drawings and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

So that those having ordinary skill in the art to which the subjectinvention appertains will more readily understand how to make and usethe same, reference may be had to the drawings wherein:

FIG. 1 is a side elevational view in cross-sectional of a prior artcheck valve having a cylindrical seating surface and a spherical valvemember which opens by moving in the downstream direction which is thedirection of fluid flow through the valve;

FIG. 2 a is a side elevational view in cross-section illustrating thecheck valve assembly of the present disclosure engaged with a fluidspray nozzle for controlling the flow of fluid through the nozzle;

FIG. 2 b is a plan view along line 2 b-2 b of FIG. 2 a illustrating thespray nozzle;

FIG. 3 a is a side elevation view in cross-section of the check valveassembly of the present disclosure with the piston disposed in a closedposition biased by spring acting in the downstream direction;

FIG. 3 b is a plan view of the downstream end of the check valveassembly of FIG. 3 a; and

FIG. 3 c is a plan view of the upstream end of the check valve of FIG. 3a illustrating the exhaust port extending through the valve body to thecentral core which houses the piston and biasing spring.

These and other features of the valve assembly of the subject inventionwill become more readily apparent to those having ordinary skill in theart from the following detailed description of preferred embodiments.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

In the description which follows, as is common in the art to which thesubject disclosure appertains, “upstream” shall refer to movement in adirection opposite the fluid flow, while “downstream” shall refer tomovement in the direction of the fluid flow. In FIGS. 1, 2 a and 3 a theupstream and downstream ends of the nozzle are identified by referencecharacters U and D respectively.

Referring now to the drawings, there is illustrated in FIG. 1 a priorart check valve designated generally as reference numeral 10. Checkvalve 10 includes a generally tubular housing 12, preferably made ofmetal, through which fluid flows in an axial direction from an upstreaminlet 14 to a downstream outlet 16. The inlet 14 is generallycylindrical and is located at the upstream end of an inlet fitting 18,threadably received in main housing member 12. The fitting 18 is formedwith a conical valve seat 20 having a taper of approximately thirtydegrees with respect to the axial center line of the valve 10. Thesmaller upstream opening 22 of the conical valve seat 20 has across-sectional area that corresponds substantially to thecross-sectional area of a pipe or tube (not shown) that would bethreaded into the inlet 14. Immediately, downstream of valve seat 20,the housing 12 is formed with a generally cylindrical portion 24 and aconical portion 26 tapering inwardly from a diameter corresponding tothe diameter of cylindrical portion 24 to a diameter corresponding tothe diameter of the pipe (not shown) which would be threaded into outlet16. That is the internal diameter of the outlet pipe is substantiallythe same as the diameter of the inlet pipe.

A relatively narrow wall 28 is formed at the downstream end of thecylindrical housing portion 24. An axial opening 30 is formed in wall 28for receiving one end of a longitudinally extending cylindrical supportelement 32 which is securely held therein.

A valve member 34 is mounted within housing 12, which includes asemi-spherical portion 36 presenting an exposed semi-spherically shapedseating surface 38. Valve member 34 also includes a cylindrical sleeveportion 40 extending axially from the flat transverse surface 42 of thesemi-spherical portion 36. The valve member 34 includes an axial opening44 that extends through the sleeve portion 40 and into thesemi-spherical portion 36, as shown in FIG. 1. The axial opening 44receives the longitudinally extending support element 32 so that thevalve member 34 is mounted therein for relative axial movement between aclosed position at which the seating surface 38 engages the conicalvalve seat 20, and an open position at which the seating surface 38 islongitudinally spaced from the valve seat 20. A biasing spring 46 isinterposed between the flat valve member surface 42 and the flangemember 28 to urge the valve member 34 toward its closed position.

In operation, once the inlet fluid pressure exceeds the mechanicalresistance imparted by biasing spring 46, valve member 34 moves in thedownstream direction toward the open position, as indicated bydirectional arrow O. Fluid which has been received into the valve 10through inlet 14 is then permitted to pass by seating surface 38 andthrough the housing 12 to outlet 16.

A disadvantage associated with check valve 10 is that since the valveopens in the downstream direction, the force imparted by valve spring 46works in counteracting the fluid flow pressure. At low operatingpressures, this can cause oscillations of the valve member 34 andtherefore, effect the constant flow requirements of the sprayed fluidand can also cause damage to the valve sealing faces. Additionally,since the valve member 34 remains at least partially within the flowpath for the fluid, it reduces the available annular flow area, whichincreases the flow velocity. An increase in flow velocity typicallyincreases the pressure loss across the valve 10 and increases thecomponent wear.

Referring now to FIGS. 2 a and 2 b, there is illustrated a check valveassembly constructed in accordance with a preferred embodiment of thesubject disclosure and designated generally as reference numeral 100. Asillustrated, check valve 100 is engaged with a spray nozzle assembly200. The disclosed check valve assembly can be used in a variety ofapplications including, but not limited to, spray or liquid flowapplications that include nozzles and orifices, such as fuel supplyapplications, industrial applications, agricultural applications andspray drying applications.

Check valve 100 is assembled from a plurality of components whichinclude, among other things, a valve body 110, an adapter 130, and avalve retainer plate 140 which when assembled combine to form a valvehousing having an interior valve chamber. Disposed within the interiorvalve chamber is a valve seat or piston 150 and a biasing spring 170.The piston 150 includes two O-ring gaskets 162 and 164 which aredisposed within peripheral grooves formed in the piston. The internalcomponents and operation of check valve 100 will be discussed in moredetail with respect to FIGS. 3 a through 3 c.

The valve body 110 has a series of female threads 124 formed in theupstream end 122 which are configured for corresponding engagement withfluid supply tubing (not shown). The adapter 130 includes two sets offemale threads 132 and 134. Threads 132 are adapted and configured forengaging with corresponding threads formed on the downstream end 126 ofthe valve body portion 110 and threads 134 engage with threadsassociated with spray nozzle 200.

Spray nozzle 200 primarily includes a nozzle body 210, a swirl unit 214for facilitating the atomization of the fluid, and an orifice disc 212for directing the discharge of the atomized fluid from the nozzle.Nozzle body 210 has a central bore 222 formed therein for receiving theorifice disc 212 and the swirl unit 214. Additionally, the downstreamend 221 of nozzle body 210 defines a spray opening 223 for emitting anatomized spray therefrom.

The orifice disc 212 is disposed within the central bore 222 of thenozzle body 210 and is positioned adjacent to the discharge portion 220.An O-ring gasket 211 is provided between the orifice disc 212 anddischarge portion 220 of the nozzle body 210. The gasket 211 provides aseal which prevents fluid from leaking around the periphery of theorifice disc 212 and between the orifice disc 212 and discharge portion220 into spray opening 223.

In the assembled configuration, the adapter member 130 is threadablyengaged with the nozzle body 210 so as to enclose the orifice disc 212and swirl unit 214 within the bore 222 of the nozzle body 210. Anadapter O-ring gasket 268 is disposed between the adapter member 130 andthe nozzle body 210 for preventing fluid leakage from the assemblednozzle 200. The spray nozzle 200 further includes a locking plate 230which is engaged with nozzle body 210.

Assembly of a conventional spray nozzle is complicated by the inabilityto properly maintain the alignment and positioning of the internalcomponents when the nozzle body is being engaged with the adapter.Locking plate 230 provides a mechanism for positively securing theorifice disc 212 and swirl unit 214 in place and compressing the orificeO-ring gasket 211 prior to threadably engaging the nozzle body 210 withthe adapter 218. The locking plate 230 is preferably manufactured from asuitable wear resistant material.

In operation, a pump (not shown) supplies liquid at an initial pressureto a flow regulator (not shown). The flow regulator then meters orcontrols the flow rate and/or adjusts the fluid pressure to the desiredsupply pressure for the check valve/spray nozzle assembly. Inlet tubing(not shown) supplies the pressurized fluid to check valve 100 whichprovides precision in the starting and stopping of the flow andminimizes dripping that can occur when the flow is suspended and/orinitiated. Check valve 100 suspends the fluid flow at a predeterminedpressure to prevent undesired spray quality and/or the dripping ofexcess spray after liquid flow is suspended. Check valve 100 is alsoconfigured to open and start the spray only when a predeterminedpressure is reached to obtain a consistent spray quality.

Upon the opening of check valve 100, fluid is supplied at the desiredpressure to spray nozzle 200. The liquid enters flow port 264 defined bythe space between swirl unit 214 and nozzle body 210. The liquid feedenters the swirl chamber of the swirl unit 214 through a fluid receivingportion and a spiral or swirl motion is imparted thereto as known tothose skilled in the art. The feed then exits the swirl chamber and isatomized by a spray orifice. Atomized feed exits the spray orifice ofthe swirl unit 214 and spray opening 223 of the nozzle body 210.

Referring now to FIGS. 3 a-3 c, there is illustrated check valve 100. Asshown therein, valve body 120 houses the components that provide theshut-off capability, namely the piston 150, biasing spring 170 and thevalve retainer plate 140. The valve body 120 has a ‘blind’ machined bore128 into which the piston 150 and spring 170 are disposed. In theembodiment disclosed herein, the bore 128 has a ‘bleed’ hole 129 (seeFIG. 3 c) that allows the air to discharge as the spring 170 iscompressed and the valve piston 150 is lifted. The bleed hole 129 isspaced from inlet flow passages 121a-122d by an angle “a”.

The piston 150 has at an upstream end 152 a location diameter that isadapted and configured for insertion into biasing spring 170. Piston 150includes two O-ring gaskets 162 and 164. O-ring gasket 162 prevents thefluid product being sprayed from exiting the nozzle when piston 150 isin the closed position, whereas the O-ring gasket 164 prevents ingressof sprayed product into the central bore 128, thus ensuring correctoperation of the biasing spring 170.

The valve retainer plate 140 is screwed into corresponding threads onthe valve body 110 and completes the valve sub-assembly. Valve retainerplate 140 compresses the spring 170 to the correct operating length andprovides a valve seat 142 which is adapted and configured for engagementwith piston 150 and O-ring gasket 162.

Fluid enters the valve body 110 through inlet bore 112 and is channeledthrough flow passages 121a-121d. On reaching the piston 150, the fluidis prevented from continuing through the assembly due to the sealingbetween the O-ring gasket 162 and the seat 142 on the valve retainerplate 140.

Providing that the pressure of the sprayed product is lower than theforce due to the compression of the biasing spring 170, no product willpass the O-ring gasket 162. However, once the pressure within thechamber 154 is raised above the pre-set spring pressure, then thebiasing spring 170 is further compressed within the bore 128 by thefluid acting on shoulder 156, thus lifting the piston 150 and allowingthe progress of the fluid through valve 100 into nozzle 200.

As long as the fluid pressure of the sprayed product remains above thecompression pressure of the spring 170 then the nozzle 100 will continueto spray product. Should the pressure be reduced, or the feed pumpstopped, then the spring 170 pushes the piston 150 back onto the seat142 of the retainer plate 140, shutting off the feed to the nozzle 200.

An advantageous feature of the check valve assembly of the presentdisclosure is the opening of the piston 150 in a direction opposite tothe flow of fluid through the nozzle 200. Valve members or pistons arenormally lifted from the valve seat in the direction of the flow (i.e.,downstream). In check valve 100, the valve seat or piston 150 is pressedin the opposite direction to the product flow or in the upstreamdirection as indicated by directional arrow “O”. This feature provides anumber of distinctive advantages over conventional valve operation.First, by removing the piston 150 from within the fluid flow path, theannular flow area is maximized. Since the flow area is not restricted bythe piston, the flow velocity is not increased locally in the sealingregion and thereby reduces the likelihood that the O-ring gasket 162will be ‘rolled’ out of the groove formed in piston 150.

Additionally, conventional check valves that open in the downstreamdirection have a tendency to oscillate at low operating pressures. Thisis due to the fact that the valve spring pressure works incounter-acting the product flow pressure. The oscillation of the valveseat can dramatically affect the constant flow requirement of thesprayed product and also cause damage to the sealing faces.

It envisioned that the biasing of the valve piston can be accomplishedby a variety of alternative methods. In addition to or in place of thehelical spring, other metal springs, elastomeric or foam elements can bepositioned with the central bore. In an alternative embodiment, thevalve body is constructed without the bleed hole which exhausts thecentral bore. As a result, air which is contained within the centralbore is compressed when the piston moves in the upstream direction,thereby acting as a spring mechanism. It is also envisioned that the airwithin the central bore can be replaced with a gas which exhibitsimproved restoration properties.

Those skilled in the art will readily appreciate that various materialscan be used for the construction of the valve components disclosedherein. Check valves wear largely depends upon its corrosion and erosionresistance. Corrosion occurs when the liquid feed and valve componentmaterial are chemically incompatible. Erosion results from the liquidfeed with its abrasive solids passing through the flow passages at highvelocities and physically removing component material. Corrosionproblems can often be avoided or at least greatly reduced by determiningthe chemical characteristics of the liquid feed. Various materials canthen be used based upon their ability to resists chemical and physicalattack. Material possibilities are too numerous to list, but thematerials disclosed herein are intended for illustrative purposes onlyand are not intended to limit the scope of the disclosure

While the invention has been described with respect to preferredembodiments, those skilled in the art will readily appreciate thatvarious changes and/or modifications can be made to the invention withdeparting from the spirit or scope of the invention as defined by theappended claims.

1. A valve assembly comprising: a) a valve body defining an axial boreand having opposed upstream and downstream end portions, the upstreamend portion including a fluid inlet, the downstream end portionincluding a fluid outlet and defining an sealing face positionedadjacent to the axial bore, the valve body further including at leastone flow passage for facilitating fluid communication between the fluidinlet and the fluid outlet; b) an elongated piston member disposed atleast partially within the axial bore of the valve body and havingopposed upstream and downstream ends, the piston member mounted formovement between an open position and a closed position, wherein thedownstream end of the piston member is spaced from the interior sealingface of the valve body in the open position to permit fluid flow throughthe valve body, and the downstream end of the piston member engages theinterior sealing face of valve body to suspend the flow of fluid throughthe valve body in the closed position; and c) biasing means operativelyassociated with the piston member for urging the piston member to theclosed position when a force impart by the biasing means on the pistonmember exceeds an opposing pressure imparted on the piston member byfluid within the flow passage.
 2. A valve assembly as recited in claim1, wherein a port is formed in the valve body, and the port extendsradially from an exterior of the valve body to the axial bore allowinggas to be exhausted therefrom.
 3. A valve assembly as recited in claim1, wherein the biasing means includes a spring element.
 4. A valveassembly as recited in claim 3, wherein the biasing means is a helicalspring.
 5. A valve assembly as recited in claim 1, wherein the biasingmeans includes a gas contained within the axial bore and compressed whenthe piston member is in the open position.
 6. A valve assembly asrecited in claim 1, wherein the downstream end of the piston memberincludes a sealing ring for engagement with the interior sealing surfaceof the valve body.
 7. A valve assembly as recited in claim 1, whereinthe biasing means is disposed within the axial bore of the valve bodyadjacent to the upstream end of the piston member.
 8. A valve assemblycomprising: a) a valve body defining an axial bore and having opposedupstream and downstream end portions, the upstream end portion includinga fluid inlet, the downstream end portion including a fluid outlet, thevalve body further defining flow passages positioned radially outward ofthe axial bore and extending axially between the fluid inlet and thefluid outlet; b) an elongated piston member disposed at least partiallywithin the axial bore of the valve body and having opposed upstream anddownstream ends, the piston member mounted for movement between an openposition and a closed position; c) biasing means operatively associatedwith the piston member for urging the piston member to the closedposition when a force impart by the biasing means on the piston memberexceeds an opposing pressure imparted on the piston member by fluidwithin the flow passage; and d) a retainer element engage with thedownstream end portion of the valve body and defining an interiorsealing face adjacent to the axial bore, the downstream end of thepiston member is spaced from the interior sealing face of the retainermember in the open position to permit fluid flow through the valve body,the downstream end of the piston member engages the interior sealingface of retainer member to suspend the flow of fluid through the valvebody in the closed position.
 9. A valve assembly as recited in claim 8,wherein a port is formed in the valve body, and the port extendsradially from an exterior of the valve body to the axial bore allowinggas to be exhausted therefrom.
 10. A valve assembly as recited in claim8, wherein the biasing means includes a spring element.
 11. A valveassembly as recited in claim 10, wherein the biasing means is a helicalspring.
 12. A valve assembly as recited in claim 8, wherein the biasingmeans includes a gas contained within the axial bore and compressed whenthe piston member is in the open position.
 13. A valve assembly asrecited in claim 8, wherein the downstream end of the piston memberincludes a sealing ring adapted and configured for engagement with theinterior sealing surface of the retainer element.
 14. A valve assemblycomprising: a) a valve body having upstream and downstream end portionsand defining an axial core and an axis for the valve assembly, the valvebody further defining flow passages extending therethrough between theupstream and downstream end portions, the downstream end portiondefining a valve seating surface adjacent to the axial core; b) a pistonmounted for axial movement within the axial core between and open and aclosed position; and c) a biasing element disposed within the axial coreand operatively associated with the piston, the biasing element forurging the piston in the closed position, the piston is engaged with theseating surface of the valve body in the closed position so as toprevent fluid flow through the valve, fluid pressure urging the pistonin the upstream direction away from the seating surface of the valvebody to the open position.
 15. A valve assembly as recited in claim 14,wherein a port is formed in the valve body, and the port extendsradially from an exterior of the valve body to the axial bore allowinggas to be exhausted therefrom.
 16. A valve assembly as recited in claim14, wherein the biasing element is a metal spring.
 17. A valve assemblyas recited in claim 16, wherein the biasing element is a helical spring.18. A valve assembly as recited in claim 14, wherein the biasing elementincludes a gas contained within the axial bore and compressed when thepiston member in the open position.